[mediaqueries] Intentional that "not" is only usable in front of a media type?

According to the grammar in Media Queries, the "not" keyword is only
allowed in front of a media type.  You can't put it in front of a set
of media features, like "not (color)".

However, as far as I can tell, using a "not" negates the entire query,
not just the type.  That is, "not screen and (color)" means "not a
color screen", rather than "not a screen, but has color".

Am I right in interpreting this?  If not, I need to revise the spec to
make this more clear.

If I am, does anyone have any clue why this grammar restriction
exists?  It seems more reasonable to let it apply to media features
without a media type as well.

~TJ